Jarvis Family Assistant is a private assistant built and used by one family. It is not a product, it is not offered to the public, and nobody outside the family can sign up for it or use it.
It helps the family with everyday things like schedules, lists and reminders. When a family member chooses to connect their own Gmail account, the assistant can read that person’s mail, read-only, so it can answer that person’s own questions about it (for example, “did the school send anything about Friday?”). It cannot send, delete, label or change any email.